This invention relates to forward looking infrared imaging systems, and particularly to such systems as may be used to enhance a vehicle operator's perception of surrounding scene features under vision-impaired conditions, e.g., rain, fog, smoke, and the like. This invention is applicable to any vehicle that is operated in vision-impaired conditions, such as trains, highway vehicles, ships, and aircraft. It is particularly applicable as an aircraft landing aid.
There is currently a commercially available aircraft landing aid that projects a synthetic representation of the runway boundaries on a pilot's head up display (HUD). This system is used to permit the pilot to bring the aircraft close enough to landing that the pilot can see the runway with the unaided eye. This system uses inertial references to sense the aircraft's location and predict where the runway should be. The system is very expensive.
Another concept has been demonstrated using millimeter wave radar to detect an airport runway and present its image on a HUD. This system's performance is marginal because of poor resolution and ambiguous detection. The millimeter wave radar can only detect the contrast between concrete and soil. The pilot cannot readily discern what part of the runway he is seeing; only that there is a strip of concrete with adjacent earth.